They also make one of the expanding foam insulation foams that keeps out insect and rodents.
Check out Stay Away or Fresh Cab from Earthkind. Earthkind.com
Hi Carolyn: here are a couple of sites that should help:
Mice hate the smell of peppermint. You can 1) saturate cotton balls with peppermint essential oil and put them at strategic places in the home or basement where you think the mice might be entering or where you see evidence of them, or 2) mix up a spray bottle with water and peppermint essential oil and spray it in those areas. I don't measure for this method. It depends on the size of the spray bottle. I just fill the bottle almost to the top with water and then add enough peppermint oil to make it smell strong enough to repel the mice. Shake before each use. *Peppermint essential oil is strong, so take care to protect your eyes and skin.